Objects not appearing when I render my model
You don't have light in your scene.

The hemi lamp in the middle of the room won't work, as cycles doesn't support hemi lamps yet. It will be treated like a sun lamp.

Sun lamps provide a uniform amount light from infinitely far away in a specific direction with no falloff. Because of this, the position of the lamp doesn't have any effect.
Since the room is completely closed and light has no way to get in from outside, everything renders as black.

If you change the lamp to a point lamp and increase the strength to something like 1000, you get something like this: